In printing presses, in order to bring the printing cylinders to and from their operating position, their bearings are mounted in eccentric rings, which in turn are rotatably mounted in the side frame of the press. In order to obtain good printing quality, it is required, inter alia, that the printing cylinders must be stabilized without play relative the side frames during operation of the press. However, a given clearance is required between the eccentric ring and the frame so that the ring can be turned when moving the cylinders to and from their operating position.
To eliminate this clearance it is known to deform either the hole wall in the press side frame or the eccentric ring.
DE Patent OS No. 26 36 555 discloses a three-point fixation of a bearing bush in a bore in a printing press side frame. Under the wall surface of the bore in the side frame there is an expansion chamber on either side of the resultant to the forces acting on the printing cylinder. By expansion of the chambers, the surfaces of the bore in the side frame which are contiguous to the chambers will expand and clamp the bush. A third support point for the bearing bush is established by the chamber walls lifting the bush on expansion into direct contact against the wall of the bore in the side frame.
The SE Patent No. 347,206 discloses a technique corresponding to DE OS No. 26 36 555, the expansion chambers being arranged in the eccentric bush for expansion of two areas of the outer cylindrical surface of the bush into contact with the wall of the bore in the side frame.
The U.S. Pat. No. 3,786,749 discloses an expansion chamber extending peripherally between said bore and an eccentric bush in a printing press.
The known arrangements for eliminating play between the eccentric ring and side frame in printing presses of the kind in question thus utilize deformation of the contiguous surfaces in question. Such deformation arrangements are expensive to produce. In the case where the deformation arrangements are of mechanical type, such as in an embodiment disclosed in DE OS No. 26 36 555, there are difficulties in guidance, and in the case of hydraulic expansion great hydraulic pressures are required, and there are substantial drawbacks in respect to establishing the hydraulic pressure. In the arrangement according to the U.S. patent, clamping of the bearing ring or bush will not be stable, since the expansion chamber is not stiff, due to the hydraulic fluid being able to move along the chamber even when under pressure. In the arrangements according to the German and the Swedish patents, the expansion chambers must be made stiff, since they shall withstand the contact pressure between the cylinders and prevent the bushes from rolling over the respective chambers.
The known art is thus complicated and expensive.